Radar and antenna built in radar

ABSTRACT

A radar includes a transmitter antenna unit that includes multiple transmitter antennas; a receiver antenna unit that includes a first receiver antenna group including multiple first receiver antennas and multiple second receiver antennas arranged at a first horizontal interval and a second receiver antenna group including multiple third receiver antennas arranged at one or more second horizontal intervals; a transceiver that transmits sending signals through the transmitter antenna unit and receives returning signals reflected from a target object trough the receiver antenna unit; and a processing unit that derives information about the target object by processing the received returning signals.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication No. PCT/KR2019/007747 filed on Jun. 26, 2019, which claimspriority to Korean Patent Application No. 10-2018-0074235 filed on Jun.27, 2018 in the Korean Intellectual Property Office, and Korean PatentApplication No. 10-2019-0075666 filed on Jun. 25, 2019 in the KoreanIntellectual Property Office, the entire disclosures of which areincorporated herein by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates to a radar and an antenna built in theradar.

BACKGROUND

In general, a radar needs to have high angular resolution to detect ortrack the distance, speed, and angle of a target device by transmittingand receiving electromagnetic waves.

Conventional radars have a structure in which multiple receiver antennasare arrayed to increase angular resolution. However, a radar having thisarray needs large-size antennas and a lot of components connected to atransceiver. Therefore, the overall size of the radar increases.

Prior Art Document 1: Korean Patent Laid-open Publication No.2019-0058072 (published on May 29, 2019)

SUMMARY

In view of the foregoing, the present disclosure provides a radar withimproved angular resolution in horizontal and vertical directions forlong-range, mid-range and short-range detection by efficiently arrangingmultiple transmitter antennas and multiple receiver antennas. Theproblems to be solved by the present disclosure are not limited to theabove-described problems. There may be other problems to be solved bythe present disclosure.

According to an exemplary embodiment, a radar may include a transmitterantenna unit that includes multiple transmitter antennas; a receiverantenna unit that includes a first receiver antenna group includingmultiple first receiver antennas and multiple second receiver antennasarranged at a first horizontal interval and a second receiver antennagroup including multiple third receiver antennas arranged at one or moresecond horizontal intervals; a transceiver that transmits sendingsignals through the transmitter antenna unit and receives returningsignals reflected from a target object trough the receiver antenna unit;and a processing unit that derives information about the target objectby processing the received returning signals.

According to another exemplary embodiment, an antenna built in a radarmay include a transmitter antenna unit that includes multipletransmitter antennas; and a receiver antenna unit that includes a firstreceiver antenna group including multiple first receiver antennas andmultiple second receiver antennas arranged at a first horizontalinterval and a second receiver antenna group including multiple thirdreceiver antennas arranged at one or more second horizontal intervals.

The above-described exemplary embodiments are provided by way ofillustration only and should not be construed as liming the presentdisclosure. Besides the above-described exemplary embodiments, there maybe additional exemplary embodiments described in the accompanyingdrawings and the detailed description.

According to the present disclosure, it is possible to improve angularresolution in horizontal and vertical directions for long-distance andnear-field detection by efficiently arranging multiple transmitterantennas and multiple receiver antennas.

Further, according to the present disclosure, the multiple transmitterantennas are vertically spaced away with a vertical offset, and, thus,it is possible to precisely detect information about an object in thevertical direction.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description that follows, embodiments are described asillustrations only since various changes and modifications will becomeapparent to those skilled in the art from the following detaileddescription. The use of the same reference numbers in different figuresindicates similar or identical items.

FIG. 1 is a block diagram of a radar in accordance with variousembodiments described herein.

FIG. 2 illustrates a first example of the array of multiple transmitterantennas and multiple receiver antennas of an antenna apparatus includedin a radar in accordance with various embodiments described herein.

FIG. 3A illustrates an embodiment of detecting horizontal informationusing the array of antennas according to the first example of thepresent disclosure.

FIG. 3B illustrates an embodiment of detecting horizontal informationusing the array of antennas according to the first example of thepresent disclosure.

FIG. 3C illustrates an embodiment of detecting horizontal informationusing the array of antennas according to the first example of thepresent disclosure.

FIG. 3D illustrates an embodiment of detecting horizontal informationusing the array of antennas according to the first example of thepresent disclosure.

FIG. 4 illustrates an antenna pattern formed by applying non-uniformlinear array interpolation in accordance with various embodimentsdescribed herein.

FIG. 5 illustrates an embodiment of detecting vertical information usingthe array of antennas according to the first example of the presentdisclosure.

FIG. 6 is a diagram illustrating a chip to which the first example ofthe present disclosure is applied.

FIG. 7 is a diagram illustrating a signal waveform of the radaraccording to the first example of the present disclosure.

FIG. 8 illustrates a second example of the array of multiple transmitterantennas and multiple receiver antennas of an antenna apparatus includedin a radar in accordance with various embodiments described herein.

DETAILED DESCRIPTION

Hereafter, example embodiments will be described in detail withreference to the accompanying drawings so that the present disclosuremay be readily implemented by those skilled in the art. However, it isto be noted that the present disclosure is not limited to the exampleembodiments but can be embodied in various other ways. In the drawings,parts irrelevant to the description are omitted for the simplicity ofexplanation, and like reference numerals denote like parts through thewhole document.

Throughout this document, the term “connected to” may be used todesignate a connection or coupling of one element to another element andincludes both an element being “directly connected” another element andan element being “electronically connected” to another element viaanother element. Further, it is to be understood that the term“comprises or includes” and/or “comprising or including” used in thedocument means that one or more other components, steps, operationand/or the existence or addition of elements are not excluded from thedescribed components, steps, operation and/or elements unless contextdictates otherwise; and is not intended to preclude the possibility thatone or more other features, numbers, steps, operations, components,parts, or combinations thereof may exist or may be added.

Throughout this document, the term “unit” includes a unit implemented byhardware and/or a unit implemented by software. As examples only, oneunit may be implemented by two or more pieces of hardware or two or moreunits may be implemented by one piece of hardware.

Throughout this document, a part of an operation or function describedas being carried out by a terminal or device may be implemented orexecuted by a server connected to the terminal or device. Likewise, apart of an operation or function described as being implemented orexecuted by a server may be so implemented or executed by a terminal ordevice connected to the server.

Hereafter, an exemplary embodiment of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a radar 100 in accordance with variousembodiments described herein.

Referring to FIG. 1, the radar 100 may include an antenna apparatus 110,a transceiver 120, a processing unit 130, a virtual receiver antennaforming unit 140, and an interpolation unit 150.

Hereafter, FIG. 1 will be described with reference to FIG. 2.

The radar 100 may be installed at a specific position of a vehicle andconfigured to transmit a sending signal through the antenna apparatus110, receive a receive signal reflected and returning from a targetobject around the vehicle, and detect the presence or absence, position,direction, or size of the target object. The target object detectionresult obtained by the radar 100 can be used to accurately control avehicle system by applying it to the vehicle system that provides acollision avoidance function for avoiding a collision with a vehicleahead, a safe lane change function, or the like.

The antenna apparatus 110 includes a transmitter antenna unit 112including multiple transmitter antennas arranged in a vertical directionand a receiver antenna unit 114 including multiple receiver antennasarranged in a horizontal direction.

The transmitter antenna unit 112 may include multiple transmitterantennas Tx1 and Tx2 that transmit sending signals to detect a targetobject. More specifically, the transmitter antenna unit 112 may includea first transmitter antenna group Tx1 arranged on the same line as thearray of multiple first receiver antennas Rx1 and a second transmitterantenna group Tx2 spaced away by a first horizontal distance from thearray of multiple second receiver antennas Rx2.

The multiple transmitter antennas Tx1 and Tx2 may be spaced away fromeach other by a predetermined distance in a vertical direction and ahorizontal direction and may have a phase difference in the verticaldirection and the horizontal direction. In this case, each of themultiple transmitter antennas Tx1 and Tx2 can perform beamforming ofsending signals in the vertical direction by a phase shift. Herein, thebeamforming of sending signals in the vertical direction can beperformed by transmitting the sending signals through the multipletransmitter antennas Tx1 and Tx2 which are spaced away from each otherby a predetermined distance in the vertical direction and have a phasedifference in the vertical direction. For example, referring to FIG. 6,multiple transmitter antennas included in each of the first transmitterantenna group Tx1 and the second transmitter antenna group Tx2 connectedto multiple chips may compensate for a phase difference caused by ahorizontal direction distance by a phase shift and then performbeamforming of sending signals in the vertical direction. In this case,if a binary phase shift is simultaneously applied to the firsttransmitter antenna group Tx1 and the second transmitter antenna groupTx2, multiple-input multiple-output (MIMO) can be implementedsimultaneously. In a first example shown in FIG. 6, an antenna structureincluding transmitter antennas and receiver antennas is implemented byusing four chips, and when the four chips are cascaded, an additionalchip may be used as a master chip for synchronization.

The multiple transmitter antennas included in each of the firsttransmitter antenna group Tx1 and the second transmitter antenna groupTx2 may be arranged in a row in the vertical direction at a firsthorizontal interval. Further, the multiple transmitter antennas includedin each of the first transmitter antenna group Tx1 and the secondtransmitter antenna group Tx2 may be spaced away with a vertical offsetat a vertical interval equal in size to the first horizontal interval.For example, if the vertical interval is 0.5 lambda, the multipletransmitter antennas included in each of the first transmitter antennagroup Tx1 and the second transmitter antenna group Tx2 may be formedinto an antenna pattern having a total vertical area of 2.5 lambda.

As shown in FIG. 2, when the multiple transmitter antennas included ineach of the first transmitter antenna group Tx1 and the secondtransmitter antenna group Tx2 are arranged and extended in the verticaldirection, the transmitter antennas can secure stability. Also, thetransmitter antennas can have a decreased field of view (FOV) in thevertical direction and thus can be less affected by clutter.

The multiple transmitter antennas included in each of the firsttransmitter antenna group Tx1 and the second transmitter antenna groupTx2 may include (m) number of antennas arranged in parallel to eachother. In the first example shown in FIG. 2, m is 6.

The first transmitter antenna group Tx1 and the second transmitterantenna group Tx2 including the multiple transmitter antennas have avertical phase difference caused by being arranged in the verticaldirection at the vertical interval equal in size to the first horizontalinterval and also have a horizontal phase difference caused by beingarranged in the horizontal direction at the first horizontal interval.In this case, each transmitter antenna channel has the horizontal phasedifference caused by the first horizontal interval in the horizontaldirection and the vertical phase direction caused by the verticalinterval equal in size to the first horizontal interval in the verticaldirection at the same time.

The multiple transmitter antennas included in each of the firsttransmitter antenna group Tx1 and the second transmitter antenna groupTx2 may have a transmitter antenna beam area from which sending signalsare transmitted in different vertical and horizontal directions.

The receiver antenna unit 114 may include multiple receiver antennasthat receive signals which were transmitted from the transmitter antennaunit 112 and then reflected and returned from the target object.

The receiver antenna unit 114 may include a first receiver antenna groupincluding multiple first receiver antennas Rx1 and multiple secondreceiver antennas Rx2 arranged at the first horizontal interval and asecond receiver antenna group including multiple third receiver antennasRx3 arranged at one or more second horizontal intervals.

The multiple first receiver antennas Rx1 included in the first receiverantenna group may include (a) number of antennas and the multiple secondreceiver antennas Rx2 may include (b) number of antennas. In the firstexample shown in FIG. 2, a is 6 and b is 4.

In the multiple first receiver antennas Rx1 and the multiple secondreceiver antennas Rx2 included in the first receiver antenna group, thesum of three single receiver antennas arranged in a row may generate asignal similar to that generated by three array antennas (e.g.,three-pronged antennas).

The multiple third receiver antennas Rx3 included in the second receiverantenna group may be arranged at the second horizontal intervals betweenthe multiple first receiver antennas Rx1 and the multiple secondreceiver antennas Rx2. Herein, if the first horizontal interval is K,the second horizontal intervals may include at least 4 K and 7 K. Themultiple third receiver antennas Rx3 included in the second receiverantenna group may include (c) number of receiver antennas each having apair of three-array antennas. In the first example shown in FIG. 2, c is6.

For example, if the first horizontal interval is 0.5 lambda, N number ofthird receiver antennas among the multiple third receiver antennas Rx3included in the second receiver antenna group may be arranged at asecond horizontal interval of 3.5 lambda and the remaining M number ofthird receiver antennas may be arranged at a second horizontal intervalof 2.0 lambda.

At least one of the multiple third receiver antennas Rx3 included in thesecond receiver antenna group may include at least three array antennas.The number of single array antennas may vary depending on an intervalbetween single array antennas. For example, if the multiple firstreceiver antennas Rx1 and the multiple second receiver antennas Rx2included in the first receiver antenna group are arranged at an intervalof 0.5 lambda and the first receiver antennas Rx1 adjacent to the thirdreceiver antennas Rx3 included in the second receiver antenna group arearranged at an interval of 1 lambda, the multiple third receiverantennas Rx3 included in the second receiver antenna group may includethree array antennas.

If each of the multiple third receiver antennas Rx3 includes three arrayantennas for each receiver channel, a receive gain can be improved.Also, beam characteristics and signal to noise ratio (SNR) can beimproved.

A long-range beam area of a typical automotive forward-looking radar isnot wide in the range of −10 degrees to +10 degrees. Therefore, whenmultiple array antennas are grouped into one antennas as long as a widefield of view (FOV) is not needed, a receive gain can be improved.Meanwhile, if an antenna includes multiple single array antennas, agrating lobe which has a bad effect on the performance of antennas mayoccur when an interval between the single array antennas is greater than0.5 lambda. However, in the present disclosure, the antennas arearranged as described above (i.e., the minimum interval between theantennas is close to 0.5 lambda). Therefore, a grating lobe can beformed far from a main beam or a main lobe. Accordingly, the horizontalresolution can be improved.

The transceiver 120 may transmit sending signals through the transmitterantenna unit 112 and receive return signals reflected from the targetobject trough the receiver antenna unit 114. For example, thetransceiver 120 may quickly transmit sending signals at a predeterminedinterval through the transmitter antenna unit 112 by a firsttransmission method (e.g., fast-chirp FMCW) as shown in FIG. 7 and mayreceive return signals reflected from the target object through thereceiver antenna unit 114.

The processing unit 130 may derive information about the target objectby processing the received return signals. For example, the processingunit 130 may acquire vertical information, such as the height of thetarget object, and horizontal information, such as the width of thetarget object, from the received return signals.

When multiple-input multiple-output (MIMO) processing is performedthrough the multiple transmitter antennas Tx1 and Tx2, the virtualreceiver antenna forming unit 140 may form one or more virtual receiverantenna groups spatially shifted by A in the same horizontal directionas the first receiver antenna group Rx1 and the second receiver antennagroup Rx2. For example, referring to FIG. 3A, when the multipletransmitter antennas Tx1 and Tx2 transmit identical sending signals atthe same time, receiver antennas configured to receive receive signalsreflected and returning from the target object based on the sendingsignals can have the same effect as if they were spatially shifted by Ain the horizontal direction and received the identical receive signals.The receiver antennas generated at the shifted positions can beexpressed as a virtual receiver antenna group VRx1, VRx2, and VRx3. Thatis, a first virtual receiver antenna VRx1 may be generated at a positionspaced away by A from the first receiver antenna group Rx1, a secondvirtual receiver antenna VRx2 may be generated at a position spaced awayby A from the second receiver antenna group Rx2, and a third virtualreceiver antenna VRx3 may be generated at a position spaced away by Afrom the third receiver antenna group Rx3. Accordingly, the firstreceiver antenna group Rx1, the second receiver antenna group Rx2, thethird receiver antenna group Rx3, the first virtual receiver antennaVRx1, the second virtual receiver antenna VRx2, and the third virtualreceiver antenna VRx3 are formed at a receiver end. Thus, an apertureextended to double horizontal area can be secured. Therefore, it ispossible to precisely measure horizontal information about the targetobject in a long distance and also possible to improve the resolution ofthe horizontal information.

The present disclosure can provide a virtual antenna structure to make aposition where a grating lobe occurs far from the center where the mainbeam is located, i.e., to suppress the occurrence of a grating lobe.

FIG. 3B to FIG. 3D illustrate various embodiments of MIMO configuration.

Referring to FIG. 3B, the transmitter antennas included in the secondtransmitter antenna group Tx2 may be arranged at a first interval whichis adjusted to locate them on the same line as some receiver antennas300 among the multiple receiver antennas included in the second receiverantenna group Rx2. A MIMO configuration shown in FIG. 3B can beconstructed by adjusting the interval between the transmitter antennas,and the formation of a virtual receiver antenna group VRx results in adouble increase in number of receiver antennas. In this case, 91receiver channels may be formed. Further, the MIMO configuration shownin FIG. 3B can use a binary phase shift (0 deg/180 deg) and can be usedas a phase reference.

Referring to FIG. 3C, the transmitter antennas included in the secondtransmitter antenna group Tx2 may be arranged at a second interval whichis adjusted to locate them on the same line as some receiver antennas310 among the multiple receiver antennas included in the second receiverantenna group Rx2. A MIMO configuration shown in FIG. 3C can beconstructed by adjusting the interval between the transmitter antennas,and the formation of a virtual receiver antenna group VRx results in adouble increase in number of receiver antennas. In this case, 88receiver channels may be formed. Further, the MIMO configuration shownin FIG. 3C can use a binary phase shift (0 deg/180 deg) and can be usedas a phase reference.

Referring to FIG. 3D, the transmitter antennas included in the secondtransmitter antenna group Tx2 may be arranged at a third interval whichis adjusted to locate them on the same line as some receiver antennas320 among the multiple receiver antennas included in the second receiverantenna group Rx2. A MIMO configuration shown in FIG. 3D can beconstructed by adjusting the interval between the transmitter antennas,and the formation of a virtual receiver antenna group VRx results in adouble increase in number of receiver antennas. In this case, 91receiver channels may be formed. Further, the MIMO configuration shownin FIG. 3D can use a binary phase shift (0 deg/180 deg) and can be usedas a phase reference.

The interpolation unit 150 may form antenna patterns arranged at thefirst horizontal interval within a horizontal area corresponding tomultiple first receiver antennas, multiple second receiver antennas, andmultiple third receiver antennas by applying non-uniform linear array(NLA) interpolation to the multiple first receiver antennas, themultiple second receiver antennas, and the multiple third receiverantennas. When the NLA interpolation is applied to the multiple receiverantennas, the maximum radiation aperture can be obtained with a limitednumber of receiver channels.

For example, referring to FIG. 2 and FIG. 4 together, if the NLAinterpolation is applied to the multiple first receiver antennas, themultiple second receiver antennas, and the multiple third receiverantennas, multiple antenna patterns may be formed at an interval of 0.5lambda within a horizontal area where the multiple first receiverantennas, the multiple second receiver antennas, and the multiple thirdreceiver antennas are located. The total horizontal interval between themultiple antenna patterns formed within the horizontal area may be 22.0lambda.

Referring to FIG. 2 and FIG. 5 together, when MIMO processing isperformed through the multiple transmitter antennas Tx1 and Tx2 arrangedat a vertical interval, the virtual receiver antenna forming unit 140may form one or more virtual receiver antenna groups VRx arranged in thesame horizontal direction as the first receiver antenna group Rx1 andthe second receiver antenna group Rx2. In this case, multiple virtualreceiver antennas included in the one or more virtual receiver antennagroups VRx formed in the same horizontal direction as the first receiverantenna group Rx1 and the second receiver antenna group Rx2 may have avertical offset at a vertical interval. Accordingly, in the presentdisclosure, it is possible to estimate the angle of the target objectusing a phase difference between the virtual receiver antenna groups VRxformed in the same horizontal direction as the first receiver antennagroup Rx1 and the second receiver antenna group Rx2 and having thevertical offset.

Referring to FIG. 2, FIG. 4, and FIG. 5 together, the virtual receiverantenna forming unit 140 may form one or more virtual receiver antennagroups VRx having a vertical offset of a vertical interval in theantenna patterns arranged at the first horizontal interval by applyingthe NLA interpolation to the multiple first receiver antennas, themultiple second receiver antennas, and the multiple third receiverantennas.

FIG. 8 illustrates a second example of the array of multiple transmitterantennas and multiple receiver antennas of the antenna apparatus 110included in a radar 200 in accordance with various embodiments describedherein. In the second example shown in FIG. 8, an antenna structureincluding transmitter antennas and receiver antennas is made intomultiple chips, and when the multiple chips are cascaded, an additionalchip may be used as a master chip for synchronization.

Referring to FIG. 8, the multiple transmitter antennas included in eachof the first transmitter antenna group Tx1 and the second transmitterantenna group Tx2 may be arranged in a row in the vertical direction atthe first horizontal interval.

Further, the multiple transmitter antennas included in each of the firsttransmitter antenna group Tx1 and the second transmitter antenna groupTx2 may be spaced away with a vertical offset of a vertical interval ofwhich size is equal to a size of the first horizontal interval.

For example, if the vertical interval is 0.5 lambda, the multipletransmitter antennas included in each of the first transmitter antennagroup Tx1 and the second transmitter antenna group Tx2 may be formedinto an antenna pattern having a total vertical area of 4.0 lambda.

The multiple transmitter antennas included in each of the firsttransmitter antenna group Tx1 and the second transmitter antenna groupTx2 may include (m) number of antennas arranged in parallel to eachother. In the second example shown in FIG. 8, m is 9.

The multiple first receiver antennas Rx1 included in the first receiverantenna group may include (a) number of antennas and the multiple secondreceiver antennas Rx2 may include (b) number of antennas. In the secondexample shown in FIG. 8, a is 5 and b is 8.

The multiple third receiver antennas Rx3 included in the second receiverantenna group may be arranged at the second horizontal intervals betweenthe multiple first receiver antennas Rx1 and the multiple secondreceiver antennas Rx2. Herein, if the first horizontal interval is K(e.g., 0.5), the second horizontal intervals may include at least 4 K, 5K, 6 K, and 11 K. The multiple third receiver antennas Rx3 included inthe second receiver antenna group may include (c) number of receiverantennas each having a pair of three-array antennas. In the secondexample shown in FIG. 8, c is 11.

above description of the present disclosure is provided for the purposeof illustration, and it would be understood by those skilled in the artthat various changes and modifications may be made without changingtechnical conception and essential features of the present disclosure.Thus, it is clear that the above-described embodiments are illustrativein all aspects and do not limit the present disclosure. For example,each component described to be of a single type can be implemented in adistributed manner. Likewise, components described to be distributed canbe implemented in a combined manner.

The scope of the present disclosure is defined by the following claimsrather than by the detailed description of the embodiment. It shall beunderstood that all modifications and embodiments conceived from themeaning and scope of the claims and their equivalents are included inthe scope of the present disclosure.

What is claimed is:
 1. A radar, comprising: a transmitter antenna unitthat includes multiple transmitter antennas; a receiver antenna unitthat includes a first receiver antenna group including multiple firstreceiver antennas and multiple second receiver antennas arranged at afirst horizontal interval and a second receiver antenna group includingmultiple third receiver antennas arranged at one or more secondhorizontal intervals; a transceiver that transmits sending signalsthrough the transmitter antenna unit and receives returning signalsreflected from a target object trough the receiver antenna unit; and aprocessing unit that derives information about the target object byprocessing the received returning signals.
 2. The radar of claim 1,wherein the multiple transmitter antennas are arranged at a verticalinterval, of which size is equal to a size of the first horizontalinterval.
 3. The radar of claim 2, further comprising: a virtualreceiver antenna forming unit that forms one or more virtual receiverantenna groups arranged in a same horizontal direction as the firstreceiver antenna group and the second receiver antenna group and havinga vertical offset of the vertical interval when multiple-inputmultiple-output processing is performed through the multiple transmitterantennas arranged at the vertical interval.
 4. The radar of claim 3,wherein at least one of the multiple third receiver antennas comprisesat least three array antennas.
 5. The radar of claim 4, wherein if thefirst horizontal interval is K, the second horizontal intervals includeat least 4 K and 7 K.
 6. The radar of claim 5, wherein the multiplethird receiver antennas are arranged at the second horizontal intervalsbetween the multiple first receiver antennas and the multiple secondreceiver antennas.
 7. The radar of claim 6, further comprising: aninterpolation unit that forms antenna patterns arranged at the firsthorizontal interval within a horizontal area corresponding to themultiple first receiver antennas, the multiple second receiver antennas,and the multiple third receiver antennas by applying non-uniform lineararray (NLA) interpolation to the multiple first receiver antennas, themultiple second receiver antennas, and the multiple third receiverantennas.
 8. The radar of claim 7, wherein the virtual receiver antennaforming unit forms one or more virtual receiver antenna groups having avertical offset of the vertical interval in the antenna patternsarranged at the first horizontal interval.
 9. An antenna built in aradar, comprising: a transmitter antenna unit that includes multipletransmitter antennas; and a receiver antenna unit that includes a firstreceiver antenna group including multiple first receiver antennas andmultiple second receiver antennas arranged at a first horizontalinterval and a second receiver antenna group including multiple thirdreceiver antennas arranged at one or more second horizontal intervals.